Urbanization and industrialization cause much air pollution in the megacities, especially those in emerging markets. To purify the ambient air in order to improve air quality, air purifiers are widely used in homes, offices and automobiles to remove, for example, dust, formaldehyde, volatile organic compounds (VOC), germs, etc. Moreover, scent dispensers are also popular; they are used to improve air quality in that they can help remove/conceal/mitigate offensive odors and thus improve people's emotional feelings.
In the existing air purifiers, the scent dispenser is typically integrated with the air purifier to help provide a pleasant smell while purifying air. The air purifier and the scent dispenser mainly operate in the following two ways. In one approach, when the air purifier operates to purify air, the scent dispenser is controlled to open up to dispense scent at a constant speed, i.e. the dispensing flow of scent dispensed by the scent dispenser is kept constant throughout the air purifying process. In the other approach, the dispensing flow of scent dispensed by the scent dispenser is controlled so as to increase with the speed of the fan of the air purifier.